Hitherto, as a connector for connecting a SM-type optical fiber single core wire and a tape core wire at low loss, for example, a multifiber connector capable of highly densely connecting optical fibers with high efficiency is used in accordance with the development of a highly dense multi-core cable that stores a single mode type optical fiber tape of four cores, eight cores, twelve cores, or the like. In a connection method, ferrules having a multi-core optical fiber positioned thereto are fitted while being positioned by two guide pins. Since the connector can be used to connect the optical fiber tape and to mechanically switch the state, the connector is called a MT connector. In recent years, the MT connector is practically used as a connector for connecting a four-core, eight-core, or twelve-core optical fiber tape of an accessing multi-core cable.
Further, in recent years, an MPO connector is also practically used which easily attach and detach a super multi-core cable by a push-pull operation. This connector is also used to connector twenty four cores and seventy two cores.
Specifically, as disclosed in Patent Document 1, there is known a ferrule for an optical connector which includes a fiber hole formed at a front end and is positioned to a counter ferrule by a fitting pin inserted into a guide pin hole. Here, the ferrule for the optical connector is obtained by the combination of a connection end of a part including the fiber hole and the guide pin hole with a rear portion of a main body of a part other than the connection. Then, the rear portion of the main body includes an inner space formed therein in a portion excluding the connection end, and the inner space includes a coating insertion portion and a boot insertion portion.
In both connectors disclosed in Patent Document 1, as illustrated in FIGS. 10A and 10B, an adhesive charging window portion 101 is provided in an upper surface of a ferrule body 100, a pair of left and right positioning guide pin insertion holes 102 is perforated from a front end surface to a rear end surface of the ferrule body 100, and a plurality of optical fiber insertion holes 103 is provided in parallel between both guide pin insertion holes 102 of the front end surface. Further, the rear end surface of the ferrule body 100 is provided with an insertion opening portion 104 which is opened in a rectangular shape and supports a rectangular tubular boot 106 (see FIGS. 9A and 9B) while inserting the rectangular tubular boot thereinto. Then, the rear end side of the ferrule body 100 is provided with a flange portion 105 which protrudes outward from the outer peripheral surface of the ferrule body 100.
Thus, as illustrated in FIGS. 9A and 9B, the boot 106 is formed in a rectangular tubular shape and the upper, lower, left, and right outer surfaces are formed as flat surfaces. Further, the longitudinal width and the lateral width of a front opening portion 107a which is elongated in the lateral direction at the front end of the boot 106 are set to dimensions corresponding to the thickness and the lateral width of the single mode type optical fiber tape T. Then, the longitudinal width of a rear opening portion 107b which is elongated in the lateral direction at the rear end of the boot 106 is slightly smaller than the longitudinal width of the front opening portion 107a of the front end so that only the twelve-core optical fiber F protruding from the front end of the single mode type optical fiber tape T protrudes outward.